40 terms

Unit 4 - Image Analysis (Review)

STUDY
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DAP is a measurement of:

A. Collimation
B. Exposure
C. Contrast
D. Brightness
B. Exposure
Define radiographic contrast:
the difference among densities seen in an image
Name and define the two types of radiographic distortion:
size: misrepresentation of the true size of the object

shape: misrepresentation of the true shape of an object due to a change in the angular relation of the tube, body part and receptor
Image "blur" is usually caused by:

A. Fog
B. equipment
C. Patient movement
D. Exposure settings
C. Patient movement
Improper alignment of a radiographic grid during digital imaging can lead to improper:

A. Spatial resolution
B. Rescaling
C. Contrast
D. Magnification
C. Contrast
Scatter radiation is very difficult to interpret during histogram analysis when it occurs:

A. Inside patient anatomy
B. Outside of the collimated field
C. Away from the image receptor
B. Outside of the collimated field
Image brightness and contrast in a digital image are not affected by which of these factors?

A. Incorrect menu selection
B. Excessive fog
C. Grid cutoff
D. Gross underexposure
D. Gross underexposure
Most digital artifacts appear:
White
Quantum noise is caused by
insufficient signal strength
Artifacts that are caused by a dirty light guide appear:

A. White and irregular
B. White and linear
C. Black and irregular
D. Black and linear
B. White and linear
_______________ ________ results from background exposure when a plate is not erased before use:

A. Scatter radiation
B. Excessive radiation
C. Excessive fog
D. Overlapping
C. Excessive fog
When the exposure absorbed by the image receptor surpasses the level at which the image receptor can respond, what is said to occur?

A. Saturation
B. Capacity
C. Fullness
D. Permeation
A. Saturation
Because PSP plates move in and out of the cassette each time the plate reader processes an image, _____________________________________ can get into the cassette.
dirt and dust
Shape distortion can be caused by:

A. Object to image receptor distance
B. Focal spot size and orientation
C. Subject- to- image receptor distance
D. Angular relationship of tube, part and image receptor.
D. Angular relationship of tube, part and image receptor.
An artifact that presents as a wavy appearance in a localized area of an image is due to:

1. Plate disruption
2. Patient movement
3. Laser disruption

A. 1 and 2
B. 1 and 3
C. 2 and 3
D. 1, 2 and 3
B. 1 and 3
In a flat-panel cassette-less system, if an individual or a row of DELs are lost, a(n) _________________________ would have to determine the repair:

A. The radiologist
B. The IR department
C. The hospital physicist
D. An engineer
D. An engineer
A lead apron in the exposure field may cause an exposure indicator miscalculation because the image data could be misrecognized as:

A. Patient motion
B. Gross overexposure
C. Gross underexposure
D. Not having collimated edges
C. Gross underexposure
Which of the following are image evaluation factors for digital imaging? Circle the one(s) that applies:

A. Density
B. Contrast
C. Image blur
D. Noise
C. Image blur
D. Noise
To reduce errors from collimation, the current recommendation is to:

A. Repeat an image until the correct factors are achieved
B. Overlap exposure fields whenever possible
C. Record one image per image receptor
D. Avoid using collimation
C. Record one image per image receptor
The definition of _________ _________ is using more than 3 times the level of radiation needed to produce a diagnostic quality image
excessive radiation
Chemicals used to clean the plate reader can ________________ a cassette.

A. Warp
B. Scratch
C. Stain
D. Distort
C. Stain
Cassette-less systems are free of artifacts.

A. True
B. False
B. False
Digital artifacts are caused by processing:

A. Appear along the entire axis of the image and on select imaging plates
B. Appear along the entire axis of the image and on every imaging plate
C. Don't cross the entire axis of the image or every imaging plate
D. Don't cross the entire axis of the image or select imaging plates
B. Appear along the entire axis of the image and on every imaging plate
How would you describe a radiologist's monitor as compared to a technologist's monitor.
quality, resolution, brightness and contrast resolution capabilities are superior
Excessive kVp, excessive mAs and the wrong grid ratio affect radiographic contrast in what way?
decreased contrast
An imbalance of scatter to remnant photons in the transmitted beam that degrades image contrast defines what:
excessive scatter
Radiographic blur can be caused by:

1. Incorrect grid ratio
2. Geometric factors
3. Patient motion

A. 1 and 2
B. 1 and 3
C. 2 and 3
D. 1, 2 and 3
C. 2 and 3
Which of these could lead to decreased density on an analog image?

A. Increased Base plus fog
B. Increased kVp
C. A low developer temperature
D. Extended processor time
C. A low developer temperature
Incorrect angulation between the tube and lead strips in the grid that results in an overall loss of radiation intensity reaching the image receptor defines:
grid cutoff
List the 4 major causes of digital artifacts in cassette-based image receptors:
dirt, scratches, bending, and staining
List the image evaluation factors for analog imaging:
density, contrast, image blur, and distortion
Inappropriate brightness on a digital image can be caused by:

1. Poor collimation
2. Poor positioning
3. Incorrect menu selection
4. Grid cutoff

A. 1, 2, 3 and 4
B. 1, 2 and 3
C. 1, 2 and 4
D. 2, 3 and 4
B. 1, 2 and 3
Most artifacts that appear when using cassette-less systems are caused by:

A. Entrance rollers
B. Static electricity
C. Dust and dirt
D. DELs
D. DELs
What error is caused by the computer's inability to identify the edges of collimation?

A. Gross overexposure
B. Gross underexposure
C. Grid cut-off
D. Exposure field recognition error
D. Exposure field recognition error
The size of the image display is affected by the size of the _______________________.
image receptor
Grid cutoff occurs when the incorrect histogram model is selected for comparison and analysis?

A. True
B. False
B. False
Excessive fog is a type of extraneous radiation that degrades contrast when added to the exposure on the image receptor.

A. True
B. False
B. False
Most artifacts that appear when using cassette-based digital imaging are cause by:

A. Patient factors
B. Entrance rollers
C. Rough handling
D. Dust and dirt
D. Dust and dirt
__________ __________ generally don't cross the entire axis of a plate
Plate artifacts
_________ _________ run along an entire plate axis
Processing artifacts
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